01 - Place all vegetable scraps, optional potato, and fresh vegetables into a large stockpot.
02 - Add bay leaves, parsley, thyme, black peppercorns, garlic, salt, and apple cider vinegar or lemon juice if using.
03 - Pour in cold water and stir to combine all ingredients.
04 - Heat over high heat until boiling, then reduce to a gentle simmer.
05 - Skim off any foam that rises within the first 10 minutes of simmering.
06 - Simmer uncovered for 60 minutes, stirring occasionally to enhance flavor extraction.
07 - Remove the pot from heat and allow the broth to cool slightly before straining.
08 - Strain the broth through a fine-mesh sieve or cheesecloth into a large bowl or container, discarding solids.
09 - Taste the broth and adjust salt or acidity as desired.
10 - Use immediately or refrigerate up to 5 days; freeze for up to 3 months.